Author

Topic: Resistor Network Brain teaser

Ti
Assimilated
Member # 941
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posted March 06, 2006 19:55
Okay, so I sort of stumped myself. I was making resistor network diagrams for people to solve (You know da kine, that you have to solve for Rt given a bunch of series and parallel resistors), and the students were given the basic equations (Series = R1 + R2 ... Parallel = (R1^1 + R2^1)^1), but there was one I devised that couldn't be solved with just those equations. I've removed all the flak, and this is what the basic catch boils down to:
I've come up with a couple of possible equations for the solution to this sort of network, but through my research can't find a clear this is the right answer for sure answer. All call physicists?
Kevin
 Check out my webpage/blog/review stash www.logichigh.com
Posts: 377  From: Sunnyvale, CA  Registered: Oct 2001
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Cap'n Vic
Member # 1477

posted March 07, 2006 11:11
Whoa! I haven’t had to exercise the old Ohm’s/Kirchoff’s law grey matter in quite a long time. This is like the M.C. Escher of circuits, I had to redraw it but it is still confusing as hell how R4 and R5 play into things.
Assume all values are 100Ω
In my drawing, R2 is in series with R5 and R4 are in parallel, the middle branch.
Middle branch: R2 + (R5 + R2)/2 100 + (100+100)/2 = 200Ω
Left (R3) and Right (R1) branches are 100Ω each. They are in parallel with the middle branch:
R3 + R1 + middle branch/3 100 + 100 + 200/3 = 133.333Ω
133.3Ω For the big ‘W’
R6 and R7 are in parallel
R6 + R7/2 100 + 100/2 = 100Ω
Soooooooooo, 133.333Ω for the Big ‘W’ + 100Ω for the bottom section equals 233.333Ω
Posts: 5471  From: One of the drones from sector 7G  Registered: Jun 2002
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quantumfluff
BlabberMouth, a Blabber Odyssey
Member # 450
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posted March 07, 2006 19:09
The nodeanalysis stuff is cool. I have not done resister networks since 1978 (back in high school) and they tried to teach physics without martix math back then.
Posts: 2902  From: 5 to 15 meters above sea level  Registered: Jun 2000
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